Hawaii, 2023

Flood in Hawaii, May 19, 2023

May 19, 2023 · NWS HFO · 1 event in 1 county or zone

A period of heavy rainfall led to road closures on the Big Island.

Where it happened

Every event with a place to put it. Tap one for its entry below.

  • Tornadoes
  • Tropical storms and surge
  • Floods
  • Wind
  • Hail
  • Winter weather
  • Heat and drought
  • Cold
  • Fire, smoke and dust
  • Marine and coastal
  • Other

Open the live radar over this ground

The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
1

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS HFO wrote it up.

A period of heavy rainfall led to road closures on the Big Island.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Honolulu, HI wrote its last area forecast discussion before the first event at May 19, 3:17 AM HST, 4 hours 17 minutes earlier.

Area forecast discussion, May 19, 3:17 AM HST, 4 hours 17 minutes before
Area Forecast Discussion
National Weather Service Honolulu HI
317 AM HST Fri May 19 2023

.SYNOPSIS...
Humid and wet conditions with light southeast winds will continue
into the weekend as an upper disturbance drifts eastward over the
state. Some showers may be heavy at times, which could lead to
localized flooding concerns today. Southeast winds will linger
into the weekend, with a transition back to easterly trade winds
and drier conditions late Saturday through early next week.

&&

.DISCUSSION...
Short-term guidance remains in good agreement through the weekend
and shows the upper low centered near Kauai drifting eastward
over the state through tonight, then opening up and shifting east
of the area over the weekend. Southerly flow ahead of it will
continue to draw deep tropical moisture northward over the
islands. This influx of moisture, coupled with enhanced lift and
added instability associated with upper height falls, will keep
the chances up for localized heavy showers and a few
thunderstorms. Early morning radar trends support this and show
plenty of moderate to heavy showers developing near the upper low
over the leeward/southern Kauai waters, with another burst of
convection located around 100 miles south of Oahu/Maui County.

The timing and spatial extent of this activity will be mostly
influenced by the progression of the aforementioned upper low
moving through. Based on the current high-resolution guidance,
the heavy showers developing over and around Niihau will continue
and gradually shift eastward to Kauai by or around daybreak, then
to Oahu and the eastern end of the state later today through
tonight. The initial concern will remain over Kauai and whether or
not the heaviest activity stays off the coast to the south or
fills in over the island this morning. If the latter scenario
evolves, the potential for localized flooding will increase,
especially since some areas have already received 2-4 inches over
the past 12 to 24 hours. A similar threat will be in place over
Oahu and Maui County through the day, then the Big Island this
evening through early Saturday. In addition to the rainfall
potential, the threat of a wintry mix remains in place over the
Big Island Summits through early Saturday as the cold pool aloft
associated with the upper low moves through.

Improving conditions are expected over the weekend through early
next week as the weakening upper low departs and upper heights
rise. This will shift the deep moisture in the area westward with
surface high pressure building to northeast. This pattern shift
will result in a more typical easterly trade wind set up with
showers returning to windward and mauka locations each day.

&&

.AVIATION...
Early this morning, light showers and layered clouds are
impacting much of the state as a low aloft moves over the islands
and tracks east through tonight. Reduced visibilities and MVFR
ceilings can be expected in and around showers tracking from the
southwest. Deeper convection is observed on radar imagery in the
waters southwest of the islands, and this activity will have the
potential to spark isolated thunderstorms and occasional heavy
rain through the morning.

Scattered shower activity and occasional MVFR conditions are
expected to continue throughout the day, particularly for the
western islands, before diminishing by tonight as the upper low
opens up and shifts east of the state. Easterly trade winds will
fill back into the region this weekend.

AIRMET Sierra remains in effect for tempo mountain obscuration
for Kauai this morning. Additionally, with thick layered clouds
overhead, light icing remains possible from roughly 13,000 through
23,000 feet statewide.

&&

.MARINE...
A surface trough will linger over western waters through today
and will produce moderate southeast to south winds across most
areas with locally fresh southeast winds across select areas of
Maui and the Big Island. The threat for isolated thunderstorms
over western waters remain and moderate rainfall will be possible
at times especially around the waters of Kauai and Oahu. The
surface trough will dissipate on Saturday, leading to a return of
easterly trade winds and Small Craft Advisory conditions possible
over typical windy waters around the Big Island and Maui county.
Trades will likely strengthen to strong speeds early next week as
high pressure strengthens far northeast of the state.

A small, short-period north-northeast swell will steadily decline
tonight through the day. Some of this swell will wrap into
exposed eastern shores, but otherwise, east shore surf will be
below May average as the nearby trade wind flow will be weaker
than normal into Saturday. A small northwest swell is possible
early next week, while returning strong trade winds will increase
east shore surf.

A mix of small south-southwest and south-southeast swell should
produce inconsistent surf near the seasonal average through
the weekend. Expect south shore surf to be at summertime
background heights from Monday through the middle of next week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

DISCUSSION...Gibbs
AVIATION...Vaughan
MARINE...Shigesato

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

1 flood. Local standard time, as filed.

Flood, Hawaii

When
May 19, 7:34 AM HST to 9:34 AM HST
Where
Hawaii County, 2.16 mi SSE of Puako to 2.46 mi ENE of Waikoloa Beach Resort
Cause
Heavy Rain
Reported by
Emergency Manager
Coordinates
19.939, -155.843

Flood waters were reported on Highway 19 between mile marker 70 and 71. Both lanes were closed due to the flooding.

What these are

Flood
Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Hawaii in 2023Every state in 2023This day in weather historyWarnings in Hawaii, May 2023

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1094088.